Soil water potential: A historical perspective and recent breakthroughs
Soil water potential: A historical perspective and recent breakthroughs
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DOI：
10.1002/vzj2.20203
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发表时间：
2022-06
影响因子：
2.8
通讯作者：
Shengmin Luo;N. Lu;Chao Zhang;W. Likos
中科院分区：
文献类型：
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作者：
Shengmin Luo;N. Lu;Chao Zhang;W. Likos
土壤水势是定义土壤水热力学状态的基石，需要量化地球浅层地下环境中的水相变、水运动、传热、电流、化学传输以及机械应力和变形等现象。这种潜力历来被概念化为储存在一定量土壤水中的自由能。尽管土壤水势的概念在过去 120 年来不断发展，但仍然缺乏一致的定义，并且一些基本问题的答案仍然存在争议和难以捉摸。土壤水自由能的来源和机制是什么？土壤水势的常见数学表达式（重力势、渗透势和基质势的叠加）能否用于定义土壤中的水相变？土壤水势的这些主要组成部分是独立的还是耦合的？非饱和条件下孔隙水压力总是拉力吗？如果是这样，土壤水密度怎么可能高达1.7 g cm−3？源自土壤颗粒周围和内部电磁场的吸附性土壤-水相互作用如何转化为机械孔隙压力？在这篇综述中，作者 (a) 对土壤水势的历史定义进行了批判性分析，以确定其优点、局限性和缺陷； (b) 综合土壤中电磁能的来源，以澄清吸附性和毛细管土壤水势机制之间的根本区别； (c) 引入最近出现的土壤基质势概念，它将吸附和毛细管作用对土壤水势的贡献统一起来； (d) 说明土壤水势统一定义的普遍性和前景，以回答水文学、地球工程和地球科学界仍然难以捉摸的一些基本问题。
Soil water potential is a cornerstone in defining the thermodynamic state of soil water required to quantify phenomena such as water phase change, water movement, heat transfer, electric current, chemical transport, and mechanical stress and deformation in the earth's shallow subsurface environment. This potential has historically been conceptualized as free energy stored in a until volume of soil water. Though the concept of soil water potential has been evolving over the past 120 yr, a consensual definition is still lacking, and answers to some fundamental questions remain controversial and elusive. What are the origins and mechanisms for the free energy of soil water? Can the common mathematical expression of soil water potential as superposition of gravitational, osmotic, and matric potentials be used to define water phase transitions in soil? Are these major components of soil water potential independent or coupled? Is pore water pressure always tensile under unsaturated conditions? If so, how can soil water density be as high as 1.7 g cm−3? How do adsorptive soil–water interactions originating from the electromagnetic field around and within soil particles transfer to mechanical pore pressure? In this review, the authors (a) provide critical analysis of historical definitions of soil water potential to identify their strengths, limitations, and flaws; (b) synthesize the origins of electromagnetic energies in soil to clarify the fundamental differences between adsorptive and capillary soil water potential mechanisms; (c) introduce a recently emerging concept of soil matric potential that unifies contributions of adsorption and capillarity to soil water potential; and (d) illustrate the generality and promise of the unified definition of soil water potential for answering some of the fundamental questions that remain elusive to the hydrology, geoengineering, and geoscience communities.